The present invention relates to providing a ribbon crossover cable assembly and method for electrically commoning corresponding ones of the contacts in a pair of electrical connectors.
When connectors are positioned one above another, such as on the back panel of an electrical device, and it is desired to have the same input or output points available on corresponding ones of the contacts of the connectors, the contacts of the connectors are wired in parallel. When each contact has a cable terminating portion of portion positioned in a single array spanning the width of a ribbon cable, with the terminating portion of contacts spaced substantially as the centerline spacing of conductors in the ribbon cable, the ribbon cable can conveniently be terminated to both connectors interconnecting corresponding ones of the contacts in the two connectors. Some prior art connectors of this type are disclosed in U.S. Pat. Nos. 3,820,055; 4,068,912; 4,241,970; and 4,410,229, the disclosures of which are hereby incorporated by reference.
However when the contacts of a connector have cable terminating portions that are not so conveniently spaced, such as the connectors disclosed in U.S. Pat. Nos. 4,243,288; 4,557,543; and 4,781,615, the disclosures of which are hereby incorporated by reference, where the contact cable terminating portions are positioned in two rows, interconnecting corresponding ones of the contacts of two connectors positioned one above the other is not as convenient.
When two ribbon cables, one for each row of contacts, are used to interconnect corresponding ones of the contacts in these latter type of connectors, the cables must cross over each other to interconnect the lower row of contacts in the lower connector with the lower row of contacts in the upper connector and the upper row of contacts in the lower connector with the upper row of contacts in the upper connector. One such method of providing a crossover using two flat cables provides a 45.degree. bend in a first one of the flat cables to cause the conductors to form a right angle. The first ribbon cable is then folded over an edge of the second ribbon cable with a second 45.degree. bend reorienting the conductors axially in the same direction albeit on the opposite side of the second cable. This method results in the conductors of the folded (first) cable being longer than the conductors of the unfolded (second) cable by at least the width of the first ribbon cable. The difference in length of the conductors can effect electrical characteristics of the conductors and the resultant signals transmitted thereover. A longer length cable for example may increase resistance and cause an increased delay in the signal being transmitted over the longer cable as compared to the delay in a signal being transmitted over the shorter cables.
It would be desirable to have a cable assembly for interconnecting contacts on connectors having two arrays of contacts and positionable one above the other wherein the length of the two ribbon cables would be substantially the same.